Methods of making and using lignin derivatives

ABSTRACT

Materials and methods for preparing reactive lignin and for preparing a bio-based adhesive are described herein.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a National Stage Application under 35 U.S.C. § 371and claims the benefit of priority to International Application No.PCT/US2016/018498, filed Feb. 18, 2016, which claims the benefit ofpriority under 35 U.S.C. § 119(e) to U.S. Application No. 62/117,625,filed on Feb. 18, 2015. The disclosure of the foregoing applications arehereby incorporated by reference in their entirety.

TECHNICAL FIELD

This disclosure generally relates to methods of making and usingreactive lignin. This disclosure also generally relates to methods ofmaking and using bio-based adhesives.

BACKGROUND

Lignin is the second most abundant natural polymer behind cellulose, yetlignin has very little commercial value despite years of research.Lignin is one of the major components of the cell wall in wood and otherplant based materials such as hemp or crop wastes. It is produced inenormous quantities each year, primarily as a by-product in the pulp andpaper industries. Lignin has little economic value and the majority oflignin is burned as a low grade fuel or is discharged into the aquaticecosystem as waste, causing a significant impact on the environment. Forexample, the majority of the Biological Oxygen Demand (BOD) from pulpmill effluents is due to waste lignin. In addition, an increase in theproduction of cellulosic ethanol from corn stalk and other biomassresources will add significantly to this glut of lignin.

This tremendous oversupply of lignin presents an enormous opportunityfor the development of renewable biomaterials to replacenon-biodegradable petroleum-based products, and the present disclosureprovides for commercially-viable and inexpensive methods of makingreactive lignin that can be used to make a wide variety of lignin-basedproducts.

In a similar vein, there is a growing demand for developingnon-petroleum-based materials to replace traditional plastics. There isa critical need to replace the commonly used formaldehyde-based resinsfound in many building materials such as plywood and particle boards.Formaldehyde-based resins have raised alarming health concerns becauseformaldehyde is highly toxic, allergenic and a classified carcinogenic.The off-gassing of formaldehyde-based resins is a significant source ofindoor air pollution, particularly from formaldehyde pressed-woodproducts.

Thus, this disclosure also describes the development of a class offormaldehyde-free, bio-based reactive adhesives for binding renewablebiodegradable material such as lignin, cellulose, wood chips and cropwaste to fabricate useful solid materials and composites.

SUMMARY

Materials and methods for preparing reactive lignin are describedherein. In addition, bio-based adhesives and methods of making suchbio-based adhesives are described herein.

In one aspect, a process for preparing a lignin derivative is provided.Such a process typically includes contacting a lignin with a diazoniumcompound of Formula I:

wherein Ar¹ is a 6-10 membered aryl substituted by 1, 2, 3, or 4independently selected R^(a) groups; L¹ is selected from the groupconsisting of —C₁₋₆ alkylene-, —Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄ alkylene-; R¹ is selected fromthe group consisting of —O—S(O)₂OH and —O—S(O)₂OR^(a); L² is selectedfrom the group consisting of a bond, —C₁₋₆ alkylene-, 6-10 memberedaryl, 5-10 membered heteroaryl, wherein the 6-10 membered aryl, 5-10membered heteroaryl is optionally substituted by 1, 2, 3, or 4independently selected R^(b) groups; each Y is independently selectedfrom the group consisting of O, S, S(O), S(O)₂, C(O), C(O)NR^(c),NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c); each R^(a) isindependently selected from the group consisting of C₁₋₆ alkyl, 6-10membered aryl, 5-10 membered heteroaryl, wherein the 6-10 membered aryl,5-10 membered heteroaryl is optionally substituted by 1, 2, 3, or 4independently selected R^(b) groups; each R^(b) is independentlyselected from the group consisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl,C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy; each R^(c)is independently selected from the group consisting of H and C₁₋₃ alkyl.

In some embodiments, the diazonium compound of Formula I is a compoundof formula Ia:

wherein: L¹ is selected from the group consisting of —C₁₋₆ alkylene-,—Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄alkylene-; R¹ is selected from the group consisting of —O—S(O)₂OH and—O—S(O)₂OR^(a); L² is selected from the group consisting of a bond,—C₁₋₆ alkylene-, 6-10 membered aryl, 5-10 membered heteroaryl, whereinthe 6-10 membered aryl, 5-10 membered heteroaryl is optionallysubstituted by 1, 2, 3, or 4 independently selected R^(b) groups; each Yis independently selected from the group consisting of O, S, S(O),S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂, andNR^(c); each R^(a) is independently selected from the group consistingof C₁₋₆ alkyl, 6-10 membered aryl, 5-10 membered heteroaryl, wherein the6-10 membered aryl, 5-10 membered heteroaryl is optionally substitutedby 1, 2, 3, or 4 independently selected R^(b) groups; each R^(b) isindependently selected from the group consisting of OH, NO₂, CN, SH,halo, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆alkoxy; and each R^(c) is independently selected from the groupconsisting of H and C₁₋₃ alkyl.

In some embodiments, the diazonium compound of Formula I is a compoundof formula Ib:

wherein: L¹ is selected from the group consisting of —C₁₋₆ alkylene-,—Y—C₁₋₆ alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄alkylene-; each Y is independently selected from the group consisting ofO, S, S(O), S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O), S(O)₂NR^(c),NR^(c)S(O)₂, and NR^(c); each R^(c) is independently selected from thegroup consisting of H and C₁₋₃ alkyl.

In some embodiments, the diazonium compound of Formula I is a compoundof formula Ic:

In some embodiments, the contacting is performed in an aqueous solution.In some embodiments, the aqueous solution has a pH of less than about 7.In some embodiments, the aqueous solution has a pH of about 4 to about5.

In some embodiments, such a process further includes forming thediazonium compound from the corresponding amine precursor prior tocontacting the lignin with the diazonium compound. In some embodiments,forming the diazonium compound from the corresponding amine precursorcomprises contacting the amine precursor with nitrous acid.

In some embodiments, such a method further includes contacting thelignin derivative with a basic aqueous solution to form an alkene ligninderivative of Formula II:

wherein: Ar¹ is a 6-10 membered aryl substituted by 1, 2, 3, or 4independently selected R^(a) groups; L¹ is selected from the groupconsisting of —C₁₋₆ alkylene-, —Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄ alkylene-; L² is selected fromthe group consisting of a bond, —C₁₋₆ alkylene-, 6-10 membered aryl,5-10 membered heteroaryl, wherein the 6-10 membered aryl, 5-10 memberedheteroaryl is optionally substituted by 1, 2, 3, or 4 independentlyselected R^(b) groups; each Y is independently selected from the groupconsisting of O, S, S(O), S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O),S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c); each R^(a) is independentlyselected from the group consisting of C₁₋₆ alkyl, 6-10 membered aryl,5-10 membered heteroaryl, wherein the 6-10 membered aryl, 5-10 memberedheteroaryl is optionally substituted by 1, 2, 3, or 4 independentlyselected R^(b) groups; each R^(b) is independently selected from thegroup consisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl, C₂₋₆ alkenyl,C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy; and each R^(c) isindependently selected from the group consisting of H and C₁₋₃ alkyl;and the wavy line indicates the point of attachment to a phenyl group ofthe lignin.

In some embodiments, the alkene lignin derivative of Formula II is acompound of formula IIa:

wherein: L¹ is selected from the group consisting of —C₁₋₆ alkylene-,—Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄alkylene-; L² is selected from the group consisting of a bond, —C₁₋₆alkylene-, 6-10 membered aryl, 5-10 membered heteroaryl, wherein the6-10 membered aryl, 5-10 membered heteroaryl is optionally substitutedby 1, 2, 3, or 4 independently selected R^(b) groups; each Y isindependently selected from the group consisting of O, S, S(O), S(O)₂,C(O), C(O)NR^(c), NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c); eachR^(b) is independently selected from the group consisting of OH, NO₂,CN, SH, halo, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ haloalkyl,and C₁₋₆ alkoxy; and each R^(c) is independently selected from the groupconsisting of H and C₁₋₃ alkyl; and the wavy line indicates the point ofattachment to a phenyl group of the lignin.

In some embodiments, the alkene lignin derivative of Formula II is acompound of formula IIb:

wherein: L¹ is selected from the group consisting of —C₁₋₆ alkylene-,—Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄alkylene-; each Y is independently selected from the group consisting ofO, S, S(O), S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O), S(O)₂NR^(c),NR^(c)S(O)₂, and NR^(c); each R^(c) is independently selected from thegroup consisting of H and C₁₋₃ alkyl; and the wavy line indicates thepoint of attachment to a phenyl group of the lignin.

In some embodiments, the alkene lignin derivative of Formula II is acompound of formula IIc:

wherein the wavy line indicates the point of attachment to a phenylgroup of the lignin.

In some embodiments, the basic aqueous solution has a pH of about 8 toabout 12. In some embodiments, contacting the lignin derivative with thebasic aqueous solution to form the alkene lignin derivative is performedat a temperature of at least about 50° C. In some embodiments,contacting the lignin derivative with the basic aqueous solution to formthe alkene lignin derivative is performed at a temperature of about 60°C. to about 80° C.

In some embodiments, such a method further includes contacting thealkene lignin derivative with a nucleophilic compound to form afunctionalized lignin. Representative nucleophilic compounds include,without limitation, a polyalcohol, a sugar alcohol, a monosaccharide, adisaccharide, an oligosaccharide, a polysaccharide, a polyether, andmixtures thereof. In some embodiments, the nucleophilic compoundcomprises at least one functional group selected from group consistingof —OH, —NH₂, —SH, —ONH₂, and —NHOH.

In some embodiments, the functionalized lignin is a compound of formulaIII:

wherein Ar¹ is a 6-10 membered aryl substituted by 1, 2, 3, or 4independently selected R^(a) groups; L¹ is selected from the groupconsisting of —C₁₋₆ alkylene-, —Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄ alkylene-; L² is selected fromthe group consisting of a bond, —C₁₋₆ alkylene-, 6-10 membered aryl,5-10 membered heteroaryl, wherein the 6-10 membered aryl, 5-10 memberedheteroaryl is optionally substituted by 1, 2, 3, or 4 independentlyselected R^(b) groups; each Y is independently selected from the groupconsisting of O, S, S(O), S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O),S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c); each R^(a) is independentlyselected from the group consisting of C₁₋₆ alkyl, 6-10 membered aryl,5-10 membered heteroaryl, wherein the 6-10 membered aryl, 5-10 memberedheteroaryl is optionally substituted by 1, 2, 3, or 4 independentlyselected R^(b) groups; each R^(b) is independently selected from thegroup consisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl, C₂₋₆ alkenyl,C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy; and each R^(c) isindependently selected from the group consisting of H and C₁₋₃ alkyl;the wavy line indicates the point of attachment to a phenyl group of thelignin; Z is selected from the group consisting of —O—, —NH—, —S—,—ONH—, and —NHO—; and group A is the nucleophilic compound.

In another aspect, a process for preparing a functionalized lignin isprovided. Such a process typically includes (i) contacting a lignin witha diazonium compound of Formula I to form a lignin derivative,

wherein: Ar¹ is a 6-10 membered aryl substituted by 1, 2, 3, or 4independently selected R^(a) groups; L¹ is selected from the groupconsisting of —C₁₋₆ alkylene-, —Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄ alkylene-; R¹ is selected fromthe group consisting of —O—S(O)₂OH and —O—S(O)₂OR^(a); L² is selectedfrom the group consisting of a bond, —C1-6 alkylene-, 6-10 memberedaryl, 5-10 membered heteroaryl, wherein the 6-10 membered aryl, 5-10membered heteroaryl is optionally substituted by 1, 2, 3, or 4independently selected R^(b) groups; each Y is independently selectedfrom the group consisting of O, S, S(O), S(O)₂, C(O), C(O)NR^(c),NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c); each R^(a) isindependently selected from the group consisting of C₁₋₆ alkyl, 6-10membered aryl, 5-10 membered heteroaryl, wherein the 6-10 membered aryl,5-10 membered heteroaryl is optionally substituted by 1, 2, 3, or 4independently selected R^(b) groups; each R^(b) is independentlyselected from the group consisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl,C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy; each R^(c)is independently selected from the group consisting of H and C₁₋₃ alkyl;(ii) contacting the lignin derivative with a basic aqueous solution toform an alkene lignin derivative of Formula II:

wherein the wavy line indicates a point of attachment to a phenyl groupof the lignin; and (iii) contacting the alkene lignin derivative with anucleophilic compound to form a functionalized lignin.

In still another aspect, a process for preparing a functionalized ligninis provided. Such a process typically includes: (i) contacting a ligninwith a diazonium compound of Formula Ic to form a lignin derivative,

wherein the contacting is performed in an aqueous solution having a pHof about 4 to about 5; (ii) contacting the lignin derivative with abasic aqueous solution at a temperature of about 60° C. to about 80° C.to form an alkene lignin derivative of Formula IIc

wherein: the wavy line indicates the point of attachment to a phenylgroup of the lignin; the basic aqueous solution has a pH of about 8 toabout 12; and (iii) contacting the alkene lignin derivative with anucleophilic compound to form a functionalized lignin.

In yet another aspect, a compound of Formula IV is provided

wherein: Ar¹ is a 6-10 membered aryl substituted by 1, 2, 3, or 4independently selected R^(a) groups; L¹ is selected from the groupconsisting of —C₁₋₆ alkylene-, —Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄ alkylene-; R¹ is selected fromthe group consisting of —O—S(O)₂OH and —O—S(O)₂OR^(a); L² is selectedfrom the group consisting of a bond, —C1-6 alkylene-, 6-10 memberedaryl, 5-10 membered heteroaryl, wherein the 6-10 membered aryl, 5-10membered heteroaryl is optionally substituted by 1, 2, 3, or 4independently selected R^(b) groups; each Y is independently selectedfrom the group consisting of O, S, S(O), S(O)₂, C(O), C(O)NR^(c),NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c); each R^(a) isindependently selected from the group consisting of C₁₋₆ alkyl, 6-10membered aryl, 5-10 membered heteroaryl, wherein the 6-10 membered aryl,5-10 membered heteroaryl is optionally substituted by 24 1, 2, 3, or 4independently selected R^(b) groups; each R^(b) is independentlyselected from the group consisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl,C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy; each R^(c)is independently selected from the group consisting of H and C₁₋₃ alkyl;and the wavy line indicates the point of attachment to a phenyl group ofa lignin.

In another aspect, a compound of Formula V is provided:

wherein the wavy line indicates the point of attachment to a phenylgroup of a lignin.

In one aspect, a bioadhesive is provided. Such a bioadhesive typicallyincludes an epoxidized vegetable oil and a vinyl sulfone precursor.Representative vegetable oils include, without limitation, soybean oil,peanut oil, canola oil, crambe oil, lesquerella oil, meadowfoam oil,rapeseed oil, sunflower oil, tall oil, sesame oil, corn oil, linseedoil, and combinations thereof.

In another aspect, a method of making a bioadhesive is provided. Such amethod typically includes combining an epoxidized vegetable oil with avinyl sulfone precursor, to thereby make a bioadhesive. In someembodiments, the combining is performed under basic conditions.Representative basic conditions include a pH of between about 8 andabout 10. In some embodiments, the combining is performed under mildheat. Representative mild heat includes a temperature of about 35° C. toabout 85° C. Generally, the combining is performed in the absence of anorganic solvent.

In yet another aspect, a method of making a biocomposite material isprovided. Such a method typically includes combining a bioadhesive asdescribed herein with a natural material to form a biocompositematerial. Such a method further can include applying pressure.Typically, the combining is performed in the absence of an organicsolvent. Typically, the bio-composite material is formaldehyde free.

Natural materials include, without limitation, wood shavings, woodchips, wood particles, pinewood shavings, hemp, waste cotton, other cropwastes. Bio-composite materials include, without limitation, woodcomposite boards, particle board, plywood, and packaging materials.Bio-composite materials also include, without limitation, absorbents,super-absorbents, bio-gels, and drug-release vehicles.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which the methods and compositions of matter belong. Althoughmethods and materials similar or equivalent to those described hereincan be used in the practice or testing of the methods and compositionsof matter, suitable methods and materials are described below. Inaddition, the materials, methods, and examples are illustrative only andnot intended to be limiting. All publications, patent applications,patents, and other references mentioned herein are incorporated byreference in their entirety.

DESCRIPTION OF DRAWINGS

Part A: Reactive Lignin

FIG. 1 is a schematic of the structures of p-coumaryl alcohol, coniferylalcohol and sinapyl alcohol.

FIG. 2 shows the 2D chemical structures (left) and the 3D ball-and-stickmodels (right) of lignin from (a) hardwood and (b) softwood.

FIG. 3 is the structure of an aromatic amine with a sulfato-ethylsulfone group.

FIG. 4 shows the reaction scheme for the preparation of reactive lignin(R=H, OMe).

FIG. 5 shows a representative reaction scheme for the reaction ofnucleophiles with reactive lignin.

FIG. 6 shows the structures of potential polyols for ligninfunctionalization.

FIG. 7 shows exemplary potential applications for reactive lignin.

Part B: Bio-Based Adhesives

FIG. 8A-8C is a synthetic scheme for making a bio-based adhesive asdescribed herein and for making bio-composite materials as describedherein.

FIG. 9 is the chemical structure of an exemplary epoxidized vegetableoil.

FIG. 10 is an exemplary reaction scheme for the methods describedherein.

FIG. 11 is a photograph of a bio-composite disk made of wood shavingsusing the methods and materials disclosed herein (compared to a USquarter).

DETAILED DESCRIPTION

Part A: Reactive Lignin

Lignin has enormous potential as a feedstock for the production ofrenewable biomaterials. Lignin is comprised of polymerized phenylpropaneunits linked through a number of different motifs of covalent bonds.Three of the common monomers of lignin are p-coumaryl alcohol, coniferylalcohol and sinapyl alcohol, which are shown in FIG. 1. These monomericalcohols, along with other minor lignin alcohols, are present in varyingamounts in the polymer matrix, depending on the source of the lignin.The monolignol units are linked together via coupling reactions to forma complex three-dimensional molecular architecture. Typical segments ofa lignin molecule are depicted in FIG. 2.

The main obstacle in developing commercially viable materials fromlignin has been how to best make the appropriate chemical modificationsfor the desired purpose or structural properties. While many aromaticsubstitution reactions require harsh conditions and/or water sensitivecatalysts, reactions with aryl diazonium salts take place in water underneutral or slightly basic pH ranges and at ambient temperatures.

The prior art describes a number of derivatives of lignin that have beenprepared for various uses. For example, a Mannich reaction withformaldehyde was used to prepare a dithiocarbamate terminated ligninderivative for scavenging heavy metal ions (Ge et al., 2014, J. Mat.Chem. A, 2:2136-45), and a similar approach was used to attach bothamine and sulfonic acid groups on lignin for heavy metal scavenging (Geet al., 2014, J. Industr. Eng. Chem., 20:4429-36; Li et al., 2015, ACSApp. Mat. Interfac., 7:15000-9). Phosphate groups also have beenincorporated into lignin to prepare halogen free flame retardants (Xinget al., 2013, J. Poly. Res., 20:234), and lignin has undergoneesterification with fatty acid chains to prepare waxy coatings for paperproducts (WO 2013/050661). Further, lignin has been used to makebio-based adhesives using formaldehyde-based resins (El Mansouri &Salvado, 2006, Industr. Crops Prod., 24:8-16), and efforts to preparelignin-derived hydrogels have been reviewed (Thakur & Thakur, 2015,Intern. J. Biol. Macromol., 72:834-47). Additionally, lignin has beenused for the controlled release of fertilizer (Mulder et al., 2011,Industr. Crops Prod., 34:915-20) and herbicides (Wang & Zhao, 2013, J.Agric. Food Chem., 61:3789-96) into the soil.

Several reviews describing current efforts to prepare value-addedproducts from lignin have been published (Laurichesse & Averous, 2014,39:1266-90; Duval & Lawoko, 2014, React. Func. Polymers, 85:78-96;Norgren & Edlund, 2014, Curr. Opin. Coll. Interf. Sci., 19:409-16), andthe intensification of research efforts into value-added products fromlignin was made evident by a review issue in the journal Green Chemistrydevoted entirely to lignin-based chemistry (Lignin Chemistry andValorization, Green Chem., 10:1). The methods described herein allow forlignin to be chemically modified easily and inexpensively such that itcan be used in numerous applications; the methods described herein areexpected to play a major role in the utilization of lignin foreconomical and practical applications.

The present document demonstrates that the aromatic rings within ligninprovide sites for electrophilic aromatic substitution reactions. Thisdisclosure describes the use of a diazonium salt prepared from abifunctional aromatic amine to make reactive lignin. This chemistry iswater-based and it requires no organic solvents. This class of moleculesis used extensively in the dye industry. In addition to the amine, theother site capable of reactivity is the nascent vinyl sulfone group,which becomes activated under basic conditions (pH 8-12) and elevatedtemperatures (60-80° C.). One example of this class of molecules isdepicted in FIG. 3.

Preparation of a reactive lignin as described herein is illustrated inFIG. 4. As shown in FIG. 4, the aromatic amine reacts with nitrous acid,which is formed by treatment of sodium nitrite with acid. The reactionproduces the diazonium salt, which then reacts with the aromatic ringsin lignin to produce the azo compound. Since a color change is typicallyobserved when a diazonium salt reacts with an aromatic ring to form theazo product, the deep purple color change in these reactions provides anindication of the success of the coupling reaction.

Importantly, the sulfato-ethyl sulfone group is stable when exposed tothe conditions under which the above-reaction takes place, but isactivated when treated with a base at elevated temperatures. Whenactivated, the sulfate ion is eliminated and a vinyl sulfone group isformed. The vinyl sulfone group acts as a Michael acceptor, andnucleophilic groups such as hydroxyls or amines will readily form a newcovalent bond with the terminal carbon as depicted in FIG. 5. If the Rgroup possesses more than one nucleophile, cross-linking can take place.

The methods described herein can be applied in numerous ways to preparevalue added products from lignin. Representative examples are shown inFIG. 7. A few examples of areas in which the described methods can beapplied include, without limitation, reaction with polyethylene glycolor polytetramethylene glycol for the fabrication of lignin co-polymersor the reaction with long chain fatty alcohols for hydrophobic coatings.Reactions with glycerol, mannitol, pentaerythritol or other inexpensivepolyols (FIG. 6) can be used for cross-linking or to provide multiplereactive sites for further functionalization, thereby leading tohydrogels and absorbents. The same polyols can be used in concert withinexpensive bio-polymers such as, without limitation, cellulose,chitosan, starch or gelatin to prepare new renewable, biodegradablebiomaterials. There are a number of polyamines that can be used in asimilar manner. In addition, the reactive lignin described herein can beused to produce absorbents or superabsorbents for use, simply by way ofexample, in the medical industry (e.g., drug delivery, wound healing).The physical properties of the materials derived from these reactionscan be manipulated by the number of equivalents of diazonium salts used,the molecular weights of the polymers, and/or the number of equivalentsof the polyols used.

The present application provides, inter alia, a process for preparing alignin derivative. The process includes contacting a lignin with adiazonium compound of Formula I:

or a salt thereof. Ar¹ is a 6-10 membered aryl substituted by 1, 2, 3,or 4 independently selected R^(a) groups. L¹ is selected from the groupconsisting of —C₁₋₆ alkylene-, —Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄ alkylene-. R¹ is selected fromthe group consisting of —O—S(O)₂OH and —O—S(O)₂OR^(a). L² is selectedfrom the group consisting of a bond, —C₁₋₆ alkylene-, 6-10 memberedaryl, 5-10 membered heteroaryl, wherein the 6-10 membered aryl, 5-10membered heteroaryl is optionally substituted by 1, 2, 3, or 4independently selected R^(b) groups. Each Y is independently selectedfrom the group consisting of O, S, S(O), S(O)₂, C(O), C(O)NR^(c),NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c). Each R^(a) isindependently selected from the group consisting of C₁₋₆ alkyl, 6-10membered aryl, 5-10 membered heteroaryl, wherein the 6-10 membered aryl,5-10 membered heteroaryl is optionally substituted by 1, 2, 3, or 4independently selected R^(b) groups. Each R^(b) is independentlyselected from the group consisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl,C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy. Each R^(c)is independently selected from the group consisting of H and C₁₋₃ alkyl.

In some embodiments, L¹ is —Y— and —Y— is S(O)₂. In some embodiment, L²is a bond.

Contacting a lignin with a compound of Formula I can result in the azocoupling of the compound of Formula I to a phenyl of the lignin asshown, for example, in FIG. 4 and Formula I-1:

In some embodiments, the diazonium compound of Formula I can be acompound of formula Ia:

or a salt thereof. L¹ can be selected from the group consisting of —C₁₋₆alkylene-, —Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄alkylene-Y—C₁₋₄ alkylene-. R¹ can be selected from the group consistingof —O—S(O)₂OH and —O—S(O)₂OR^(a). L² can be selected from the groupconsisting of a bond, —C₁₋₆ alkylene-, 6-10 membered aryl, 5-10 memberedheteroaryl, wherein the 6-10 membered aryl, 5-10 membered heteroaryl canbe optionally substituted by 1, 2, 3, or 4 independently selected R^(b)groups. Each Y can be independently selected from the group consistingof O, S, S(O), S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O), S(O)₂NR^(c),NR^(c)S(O)₂, and NR^(c). Each R^(a) can be independently selected fromthe group consisting of C₁₋₆ alkyl, 6-10 membered aryl, 5-10 memberedheteroaryl, wherein the 6-10 membered aryl, 5-10 membered heteroaryl canbe optionally substituted by 1, 2, 3, or 4 independently selected R^(b)groups. Each R^(b) can be independently selected from the groupconsisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy. Each R^(c) can beindependently selected from the group consisting of H and C₁₋₃ alkyl.

In some embodiments, L¹ is —Y— and —Y— is S(O)₂. In some embodiment, L²is a bond.

In some embodiments, the diazonium compound of Formula I is a compoundof formula Ib:

or a salt thereof. L¹ can be selected from the group consisting of —C₁₋₆alkylene-, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄alkylene-Y—C₁₋₄ alkylene-. Each Y can be independently selected from thegroup consisting of O, S, S(O), S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O),S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c). R^(c) can be independentlyselected from the group consisting of H and C₁₋₃ alkyl.

In some embodiments the diazonium compound of Formula I is a compound offormula Ic:

or a salt thereof.

Contacting a lignin with a compound of Formula Ic can result in the azocoupling of the compound of Formula Ic to an aromatic moiety of thelignin as shown, for example, in FIG. 4 and Formula Ic-1:

In some embodiments, the contacting is performed in an aqueous solution.The aqueous solution can have a pH of less than about 7. For example,the aqueous solution can have a pH of about 3 to about 6 or about 4 toabout 5. The pH of the aqueous solution can be adjusted with a buffersuch as sodium bicarbonate.

In some embodiments, the contacting is not performed in the presence ofany organic solvents.

In some embodiments, the reaction of the diazonium compound with thelignin is performed for a period of less than about 5 hours, less thanabout 4 hours, less than about 3 hours, less than about 2 hours, or lessthan about 1 hour.

In some embodiments, the diazonium compound can be formed from thecorresponding amine precursor prior to contacting the lignin with thediazonium compound as shown, for example, in FIG. 4. For example, thediazonium compound can be formed from the corresponding amine precursorby contacting the amine precursor with nitrous acid.

The process can further include contacting the lignin derivative with abasic aqueous solution to form an alkene lignin derivative of FormulaII:

Ar¹ can be a 6-10 membered aryl substituted by 1, 2, 3, or 4independently selected R^(a) groups. L¹ can be selected from the groupconsisting of —C₁₋₆ alkylene-, —Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄ alkylene-. L² can be selectedfrom the group consisting of a bond, —C₁₋₆ alkylene-, 6-10 memberedaryl, 5-10 membered heteroaryl, wherein the 6-10 membered aryl, 5-10membered heteroaryl can be optionally substituted by 1, 2, 3, or 4independently selected R^(b) groups. Each Y can be independentlyselected from the group consisting of O, S, S(O), S(O)₂, C(O),C(O)NR^(c), NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c). Each R^(a)can be independently selected from the group consisting of C₁₋₆ alkyl,6-10 membered aryl, 5-10 membered heteroaryl, wherein the 6-10 memberedaryl, 5-10 membered heteroaryl can be optionally substituted by 1, 2, 3,or 4 independently selected R^(b) groups. Each R^(b) can beindependently selected from the group consisting of OH, NO₂, CN, SH,halo, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆alkoxy. Each R^(c) can be independently selected from the groupconsisting of H and C₁₋₃ alkyl. The wavy line can indicate a point ofattachment to a phenyl group of the lignin.

For example, an alkene lignin derivative of Formula II can have theFormula II-1:

In some embodiments, L¹ is —Y— and —Y— is S(O)₂. In some embodiment, L²is a bond.

In some embodiments, the alkene lignin derivative of Formula II is acompound of formula IIa:

L¹ can be selected from the group consisting of —C₁₋₆ alkylene-, —Y—,—Y—C₁₋₆ alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄alkylene-. L² can be selected from the group consisting of a bond, —C₁₋₆alkylene-, 6-10 membered aryl, 5-10 membered heteroaryl, wherein the6-10 membered aryl, 5-10 membered heteroaryl can be optionallysubstituted by 1, 2, 3, or 4 independently selected R^(b) groups. Each Ycan be independently selected from the group consisting of O, S, S(O),S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂, andNR^(c). Each R^(b) can be independently selected from the groupconsisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy. Each R^(c) can beindependently selected from the group consisting of H and C₁₋₃ alkyl.The wavy line can indicate a point of attachment to a phenyl group ofthe lignin.

In some embodiments, L¹ is —Y— and —Y— is S(O)₂. In some embodiment, L²is a bond.

In some embodiments, the alkene lignin derivative of Formula II is acompound of formula IIb:

L¹ can be selected from the group consisting of —C₁₋₆ alkylene-, —Y—,—Y—C₁₋₆ alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄alkylene-. Each Y can be independently selected from the groupconsisting of O, S, S(O), S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O),S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c). Each R^(c) can be independentlyselected from the group consisting of H and C₁₋₃ alkyl. The wavy linecan indicate a point of attachment to a phenyl group of the lignin.

In some embodiments, the alkene lignin derivative of Formula II is acompound of formula IIc:

The wavy line can indicate a point of attachment to a phenyl group ofthe lignin.

For example, the alkene lignin derivative of Formula IIc can have theFormula IIc-1:

In some embodiments, the basic aqueous solution has a pH of about 8 toabout 12. In some embodiments, contacting the lignin derivative with thebasic aqueous solution to form the alkene lignin derivative is performedat a temperature of at least about 50° C. For example, contacting thelignin derivative with the basic aqueous solution to form the alkenelignin derivative can be performed at a temperature of about 60° C. toabout 80° C.

The process can further include contacting the alkene lignin derivativewith a nucleophilic compound to form a functionalized lignin. Thenucleohilic compound can be any compound capable of undergoing a Michaeladdition with the alkene of the alkene lignin derivative (e.g., thealkene of a vinyl sulfone). In some embodiments, the nucleophiliccompound can be selected from the group consisting of a polyalcohol, asugar alcohol, a monosaccharide, a disaccharide, an oligosaccharide, apolysaccharide, a polyether, and mixtures thereof. In some embodiments,the nucleophilic compound includes at least one functional groupselected from group consisting of —OH, —NH₂, —SH, —ONH₂, and —NHOH. Forexample, the nucleophilic compound can includes at least one functionalgroup selected from group consisting of —OH, —NH₂, and —SH. Thenucleophilic compound can includes at least one functional groupselected from group consisting of —OH and —NH₂.

In some embodiments, the functionalized lignin is a compound of formulaIII:

Ar¹ can be a 6-10 membered aryl substituted by 1, 2, 3, or 4independently selected R^(a) groups. L¹ can be selected from the groupconsisting of —C₁₋₆ alkylene-, —Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄ alkylene-. L² can be selectedfrom the group consisting of a bond, —C₁₋₆ alkylene-, 6-10 memberedaryl, 5-10 membered heteroaryl, wherein the 6-10 membered aryl, 5-10membered heteroaryl is optionally substituted by 1, 2, 3, or 4independently selected R^(b) groups. Each Y can be independentlyselected from the group consisting of O, S, S(O), S(O)₂, C(O),C(O)NR^(c), NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c). Each R^(a)can be independently selected from the group consisting of C₁₋₆ alkyl,6-10 membered aryl, 5-10 membered heteroaryl, wherein the 6-10 memberedaryl, 5-10 membered heteroaryl can be optionally substituted by 1, 2, 3,or 4 independently selected R^(b) groups. Each R^(b) can beindependently selected from the group consisting of OH, NO₂, CN, SH,halo, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆alkoxy. Each R^(c) can be independently selected from the groupconsisting of H and C₁₋₃ alkyl. The wavy line can indicate a point ofattachment to a phenyl group of the lignin. Z can be selected from thegroup consisting of —O—, —NH—, —S—, —ONH—, and —NHO—. Group A can be thenucleophilic compound.

For example, the functionalized lignin compound of Formula III can havethe Formula III-1.

In some embodiments, the functionalized lignin is a compound of formulaIIIa:

L¹ can be selected from the group consisting of —C₁₋₆ alkylene-, —Y—,—Y—C₁₋₆ alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄alkylene-. L² can be selected from the group consisting of a bond, —C₁₋₆alkylene-, 6-10 membered aryl, 5-10 membered heteroaryl, wherein the6-10 membered aryl, 5-10 membered heteroaryl can be optionallysubstituted by 1, 2, 3, or 4 independently selected R^(b) groups. Each Ycan be independently selected from the group consisting of O, S, S(O),S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂, andNR^(c). Each R^(b) can be independently selected from the groupconsisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy. Each R^(c) can beindependently selected from the group consisting of H and C₁₋₃ alkyl.The wavy line can indicate a point of attachment to a phenyl group ofthe lignin. Z can be selected from the group consisting of —O—, —NH—,—S—, —ONH—, and —NHO—. Group A can be the nucleophilic compound.

In some embodiments, the functionalized lignin is a compound of formulaIIIb:

L¹ can be selected from the group consisting of —C₁₋₆ alkylene-, —Y—,—Y—C₁₋₆ alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄alkylene-. Each Y can be independently selected from the groupconsisting of O, S, S(O), S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O),S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c). Each R^(c) can be independentlyselected from the group consisting of H and C₁₋₃ alkyl. The wavy linecan indicate a point of attachment to a phenyl group of the lignin. Zcan be selected from the group consisting of —O—, —NH—, —S—, —ONH—, and—NHO—. Group A can be the nucleophilic compound.

In some embodiments, the functionalized lignin is a compound of FormulaIIIc:

The wavy line can indicate a point of attachment to a phenyl group ofthe lignin. Z can be selected from the group consisting of —O—, —NH—,—S—, —ONH—, and —NHO—. Group A can be the nucleophilic compound.

For example, the functionalized lignin compound of Formula III can havethe Formula IIIc-1.

The present application provides a process for preparing afunctionalized lignin. The process includes contacting a lignin with adiazonium compound of Formula I:

or a salt thereof, to form a lignin derivative. The process furtherincludes contacting the lignin derivative with a basic aqueous solutionto form an alkene lignin derivative of Formula II:

The process further includes contacting the alkene lignin derivative ofFormula II with a nucleophilic compound to form a functionalized ligninvia the Michael addition of the nucleophilic compound to the alkene ofthe lignin derivative of Formula II. Ar¹ is a 6-10 membered arylsubstituted by 1, 2, 3, or 4 independently selected R^(a) groups. L¹ isselected from the group consisting of —C₁₋₆ alkylene-, —Y—, —Y—C₁₋₆alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄ alkylene-. R¹is selected from the group consisting of —O—S(O)₂OH and —O—S(O)₂OR^(a).L² is selected from the group consisting of a bond, —C1-6 alkylene-,6-10 membered aryl, 5-10 membered heteroaryl, wherein the 6-10 memberedaryl, 5-10 membered heteroaryl is optionally substituted by 1, 2, 3, or4 independently selected R^(b) groups. Each Y is independently selectedfrom the group consisting of O, S, S(O), S(O)₂, C(O), C(O)NR^(c),NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c). Eeach R^(a) isindependently selected from the group consisting of C₁₋₆ alkyl, 6-10membered aryl, 5-10 membered heteroaryl, wherein the 6-10 membered aryl,5-10 membered heteroaryl is optionally substituted by 1, 2, 3, or 4independently selected R^(b) groups. Each R^(b) is independentlyselected from the group consisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl,C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy. Each R^(c)is independently selected from the group consisting of H and C₁₋₃ alkyl.The wavy line indicates a point of attachment to a phenyl group of thelignin.

In some embodiments, the functionalized lignin is a compound of formulaIII:

Z can be selected from the group consisting of —O—, —NH—, —S—, —ONH—,and —NHO—. Group A can be the nucleophilic compound.

The present application also provides a process for preparing afunctionalized lignin. The process includes contacting a lignin with adiazonium compound of Formula Ic

or a salt thereof, in an aqueous solution having a pH of about 4 toabout 5 to form a lignin derivative. The process further includescontacting the lignin derivative with a basic aqueous solution at atemperature of about 60° C. to about 80° C. to form an alkene ligninderivative of Formula IIc

The wavy line indicates the point of attachment to a phenyl group of thelignin. The basic aqueous solution has a pH of about 8 to about 12. Theprocess further includes contacting the alkene lignin derivative with anucleophilic compound to form a functionalized lignin.

In some embodiments, the functionalized lignin is a compound of FormulaIIIc:

The wavy line can indicate a point of attachment to a phenyl group ofthe lignin. Z can be selected from the group consisting of —O—, —NH—,—S—, —ONH—, and —NHO—. Group A can be the nucleophilic compound.

For example, the functionalized lignin compound of Formula III can havethe Formula IIIc-1.

The present application also provides a compound of Formula IV:

Ar¹ is a 6-10 membered aryl substituted by 1, 2, 3, or 4 independentlyselected R^(a) groups. L¹ is selected from the group consisting of —C₁₋₆alkylene-, —Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄alkylene-Y—C₁₋₄ alkylene-. R¹ is selected from the group consisting of—O—S(O)₂OH and —O—S(O)₂OR^(a). L² is selected from the group consistingof a bond, —C1-6 alkylene-, 6-10 membered aryl, 5-10 memberedheteroaryl, wherein the 6-10 membered aryl, 5-10 membered heteroaryl isoptionally substituted by 1, 2, 3, or 4 independently selected R^(b)groups. Each Y is independently selected from the group consisting of O,S, S(O), S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂,and NR^(c). Each R^(a) is independently selected from the groupconsisting of C₁₋₆ alkyl, 6-10 membered aryl, 5-10 membered heteroaryl,wherein the 6-10 membered aryl, 5-10 membered heteroaryl is optionallysubstituted by 24 1, 2, 3, or 4 independently selected R^(b) groups.Each R^(b) is independently selected from the group consisting of OH,NO₂, CN, SH, halo, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄haloalkyl, and C₁₋₆ alkoxy. Each R^(c) is independently selected fromthe group consisting of H and C₁₋₃ alkyl. The wavy line indicates thepoint of attachment to a phenyl group of a lignin.

The present application also provides a compound of Formula V:

The wavy line indicates the point of attachment to a phenyl group of alignin.Definitions

The term “n-membered” where n is an integer typically describes thenumber of ring-forming atoms in a moiety where the number ofring-forming atoms is n. For example, piperidinyl is an example of a6-membered heterocycloalkyl ring, pyrazolyl is an example of a5-membered heteroaryl ring, pyridyl is an example of a 6-memberedheteroaryl ring, and naphthalene is an example of a 10-membered arylgroup.

As used herein, the phrase “optionally substituted” means unsubstitutedor substituted. As used herein, the term “substituted” means that ahydrogen atom is removed and replaced by a substituent. It is to beunderstood that substitution at a given atom is limited by valency.

Throughout the definitions, the term “C_(n-m)” indicates a range whichincludes the endpoints, wherein n and m are integers and indicate thenumber of carbons. Examples include C₁₋₄, C₁₋₆, and the like.

As used herein, the term “C_(n-m) alkyl”, employed alone or incombination with other terms, refers to a saturated hydrocarbon groupthat may be straight-chain or branched, having n to m carbons. Examplesof alkyl moieties include, but are not limited to, chemical groups suchas methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl,sec-butyl; higher homologs such as 2-methyl-1-butyl, n-pentyl, 3-pentyl,n-hexyl, 1,2,2-trimethylpropyl, and the like. In some embodiments, thealkyl group contains from 1 to 6 carbon atoms, from 1 to 4 carbon atoms,from 1 to 3 carbon atoms, or 1 to 2 carbon atoms.

As used herein, “C_(n-m) alkenyl” refers to an alkyl group having one ormore double carbon-carbon bonds and having n to m carbons. Examplealkenyl groups include, but are not limited to, ethenyl, n-propenyl,isopropenyl, n-butenyl, sec-butenyl, and the like. In some embodiments,the alkenyl moiety contains 2 to 6, 2 to 4, or 2 to 3 carbon atoms.

As used herein, “C_(n-m) alkynyl” refers to an alkyl group having one ormore triple carbon-carbon bonds and having n to m carbons. Examplealkynyl groups include, but are not limited to, ethynyl, propyn-1-yl,propyn-2-yl, and the like. In some embodiments, the alkynyl moietycontains 2 to 6, 2 to 4, or 2 to 3 carbon atoms.

As used herein, the term “C_(n-m) alkylene”, employed alone or incombination with other terms, refers to a divalent alkyl linking grouphaving n to m carbons. Examples of alkylene groups include, but are notlimited to, ethan-1,1-diyl, ethan-1,2-diyl, propan-1,1,-diyl,propan-1,3-diyl, propan-1,2-diyl, butan-1,4-diyl, butan-1,3-diyl,butan-1,2-diyl, 2-methyl-propan-1,3-diyl, and the like. In someembodiments, the alkylene moiety contains 2 to 6, 2 to 4, 2 to 3, 1 to6, 1 to 4, or 1 to 2 carbon atoms.

As used herein, the term “C_(n-m) alkoxy”, employed alone or incombination with other terms, refers to a group of formula —O-alkyl,wherein the alkyl group has n to m carbons. Example alkoxy groupsinclude, but are not limited to, methoxy, ethoxy, propoxy (e.g.,n-propoxy and isopropoxy), butoxy (e.g., n-butoxy and tert-butoxy), andthe like. In some embodiments, the alkyl group has 1 to 6, 1 to 4, or 1to 3 carbon atoms.

As used herein, “halo” refers to F, Cl, Br, or I. In some embodiments, ahalo is F, Cl, or Br. In other embodiments, halo is F, Cl, or I. Inother embodiments, halo is F, I, or Br.

As used herein, the term “C_(n-m) haloalkyl”, employed alone or incombination with other terms, refers to an alkyl group having from onehalogen atom to 2s+1 halogen atoms which may be the same or different,where “s” is the number of carbon atoms in the alkyl group, wherein thealkyl group has n to m carbon atoms. In some embodiments, the haloalkylgroup is fluorinated only. In some embodiments, the alkyl group has 1 to6, 1 to 4, or 1 to 3 carbon atoms.

As used herein, the term “amino” refers to a group of formula —NH₂.

As used herein, the term “thio” refers to a group of formula —SH.

As used herein, the term “cyano” refers to a group of formula —CN.

As used herein, “cycloalkyl” refers to non-aromatic cyclic hydrocarbonsincluding cyclized alkyl and/or alkenyl groups. Cycloalkyl groups caninclude mono- or polycyclic (e.g., having 2, 3 or 4 fused rings) groupsand spirocycles. Ring-forming carbon atoms of a cycloalkyl group can beoptionally substituted by oxo or sulfido (e.g., C(O) or C(S)). Alsoincluded in the definition of cycloalkyl are moieties that have one ormore aromatic rings fused (i.e., having a bond in common with) to thecycloalkyl ring, for example, benzo or thienyl derivatives ofcyclopentane, cyclohexane, and the like. A cycloalkyl group containing afused aromatic ring can be attached through any ring-forming atomincluding a ring-forming atom of the fused aromatic ring. Cycloalkylgroups can have 3, 4, 5, 6, 7, 8, 9, or 10 ring-forming carbons (C₃₋₁₀).In some embodiments, the cycloalkyl is a C₃₋₁₀ monocyclic or bicycliccyclocalkyl. In some embodiments, the cycloalkyl is a C₃₋₇ monocycliccyclocalkyl. Example cycloalkyl groups include cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclopentenyl, cyclohexenyl,cyclohexadienyl, cycloheptatrienyl, norbornyl, norpinyl, norcarnyl, andthe like. In some embodiments, cycloalkyl is cyclopropyl, cyclobutyl,cyclopentyl, or cyclohexyl.

As used herein, “aryl,” refers to cyclic aromatic hydrocarbons that donot contain heteroatoms in the ring. Thus aryl groups include, but arenot limited to, phenyl, azulenyl, heptalenyl, biphenyl, indacenyl,fluorenyl, phenanthrenyl, triphenylenyl, pyrenyl, naphthacenyl,chrysenyl, biphenylenyl, anthracenyl, and naphthyl groups. In someembodiments, aryl groups contain about 6 to about 14 carbons in the ringportions of the groups. Aryl groups can be unsubstituted or substituted,as defined herein. Representative substituted aryl groups can bemono-substituted or substituted more than once, such as, but not limitedto, 2-, 3-, 4-, 5-, or 6-substituted phenyl or 2-8 substituted naphthylgroups, which can be substituted with carbon or non-carbon groups suchas those listed herein

As used herein, “heteroaryl” refers to a monocyclic or polycyclicaromatic heterocycle having at least one heteroatom ring member selectedfrom sulfur, oxygen, and nitrogen. In some embodiments, the heteroarylring has 1, 2, 3, or 4 heteroatom ring members independently selectedfrom nitrogen, sulfur and oxygen. In some embodiments, any ring-formingN in a heteroaryl moiety can be an N-oxide. In some embodiments, theheteroaryl is a 5-10 membered monocyclic or bicyclic heteroaryl having1, 2, 3 or 4 heteroatom ring members independently selected fromnitrogen, sulfur and oxygen. In some embodiments, the heteroaryl is a5-6 monocyclic heteroaryl having 1 or 2 heteroatom ring membersindependently selected from nitrogen, sulfur and oxygen. In someembodiments, the heteroaryl is a five-membered or six-memberedheteroaryl ring. A five-membered heteroaryl ring is a heteroaryl with aring having five ring atoms wherein one or more (e.g., 1, 2, or 3) ringatoms are independently selected from N, O, and S. Exemplaryfive-membered ring heteroaryls are thienyl, furyl, pyrrolyl, imidazolyl,thiazolyl, oxazolyl, pyrazolyl, isothiazolyl, isoxazolyl,1,2,3-triazolyl, tetrazolyl, 1,2,3-thiadiazolyl, 1,2,3-oxadiazolyl,1,2,4-triazolyl, 1,2,4-thiadiazolyl, 1,2,4-oxadiazolyl, 1,3,4-triazolyl,1,3,4-thiadiazolyl, and 1,3,4-oxadiazolyl. A six-membered heteroarylring is a heteroaryl with a ring having six ring atoms wherein one ormore (e.g., 1, 2, or 3) ring atoms are independently selected from N, O,and S. Exemplary six-membered ring heteroaryls are pyridyl, pyrazinyl,pyrimidinyl, triazinyl and pyridazinyl.

As used herein, “heterocycloalkyl” refers to non-aromatic monocyclic orpolycyclic heterocycles having one or more ring-forming heteroatomsselected from O, N, or S. Included in heterocycloalkyl are monocyclic4-, 5-, 6-, 7-, 8-, 9- or 10-membered heterocycloalkyl groups.Heterocycloalkyl groups can also include spirocycles. Exampleheterocycloalkyl groups include pyrrolidin-2-one,1,3-isoxazolidin-2-one, pyranyl, tetrahydropuran, oxetanyl, azetidinyl,morpholino, thiomorpholino, piperazinyl, tetrahydrofuranyl,tetrahydrothienyl, piperidinyl, pyrrolidinyl, isoxazolidinyl,isothiazolidinyl, pyrazolidinyl, oxazolidinyl, thiazolidinyl,imidazolidinyl, azepanyl, benzazapene, and the like. Ring-forming carbonatoms and heteroatoms of a heterocycloalkyl group can be optionallysubstituted by oxo or sulfido (e.g., C(O), S(O), C(S), or S(O)₂, etc.).The heterocycloalkyl group can be attached through a ring-forming carbonatom or a ring-forming heteroatom. In some embodiments, theheterocycloalkyl group contains 0 to 3 double bonds. In someembodiments, the heterocycloalkyl group contains 0 to 2 double bonds.Also included in the definition of heterocycloalkyl are moieties thathave one or more aromatic rings fused (i.e., having a bond in commonwith) to the cycloalkyl ring, for example, benzo or thienyl derivativesof piperidine, morpholine, azepine, etc. A heterocycloalkyl groupcontaining a fused aromatic ring can be attached through anyring-forming atom including a ring-forming atom of the fused aromaticring. In some embodiments, the heterocycloalkyl is a monocyclic 4-6membered heterocycloalkyl having 1 or 2 heteroatoms independentlyselected from nitrogen, oxygen, or sulfur and having one or moreoxidized ring members. In some embodiments, the heterocycloalkyl is amonocyclic or bicyclic 4-10 membered heterocycloalkyl having 1, 2, 3, or4 heteroatoms independently selected from nitrogen, oxygen, or sulfurand having one or more oxidized ring members.

Part B: Bio-Based Adhesives

Bio-based adhesives are disclosed that can be made from epoxidizedvegetable oils and a suitable bi-functional linker. These bio-basedadhesives can be combined with one or more natural materials (e.g.,renewable materials that includes cellulose, lignin, or other proteins,e.g., wood shavings, hemp) to fabricate biodegradable bio-compositematerials including, for example, particle board, plywood, andcellulose-based packaging material. Importantly, both the bio-basedadhesives as well as the bio-composite materials made with suchbio-based adhesives are formaldehyde-free. Given the ingredients used inthe bio-based adhesives described herein, they also can be used inedible compositions (e.g., as edible adhesives).

FIG. 8 is a schematic showing the reactions described herein resultingin the bio-based adhesives as well as bio-composites that include suchbio-based adhesives. First, epoxidized vegetable oil (e.g., commerciallyavailable from, e.g., The Chemical Co., Jamestown, R.I.; or Arkema,France) is reacted with an excess of a suitable bi-functional linker(FIG. 8A). As shown in FIG. 8A, the suitable bi-functional linkerincludes vinyl sulfone precursors. As shown in FIG. 8B, the nitrogenatom of the vinyl sulfone precursors attack and open up the threemembered epoxide rings in the oil by forming carbon-nitrogen covalentbonds. This leads to the incorporation of the vinyl sulfone precursorinto the fatty acid side chains of the vegetable oil to form thevegetable oil-based cross-linker (FIG. 8B). It would be appreciated by askilled artisan that follow-up treatments of this compound in thepresence of a base remove the sulfonic acids. FIG. 8C shows the chemicalreaction that the vegetable oil-based cross-linking agent undergoes inthe presence of cellulose.

The bio-based adhesives described herein also can be used to produceother biomaterials for consumer applications such as super-absorbentmaterials, bio-gels, or vehicles for drug-release formulations.

Epoxidized Vegetable Oils

An example of an epoxidized vegetable oil is shown in FIG. 9. Thevegetable oil shown in FIG. 9 is one embodiment of an epoxidized soybeanoil. The compound is a triglyceride made up of glycerin with three fattyacid esters. The original sites of unsaturation have been converted tothe reactive epoxide functional group.

In addition to the soyben oil shown in FIG. 9, a number of othervegetable oils can be used. For example, peanut oil, canola oil, crambeoil, lesquerella oil, meadowfoam oil, rapeseed oil, sunflower oil, talloil, sesame oil, corn oil, linseed oil, or combinations thereof can beused in the bio-based adhesives described herein. It would be understoodthat expoxidized vegetable oils are commercially available, or,alternatively, a vegetable oil can be epoxidized using routine methods.See, for example, Saremi et al. (2012, “Epoxidation of Soybean Oil,”Annals of Biol. Res., 3(9):4254-8) and Saithai et al. (2013, “Effects ofdifferent epoxidation methods of soybean oil on the characteristics ofacrylated epoxidized soybean oil-co-poly(methyl methacrylate)copolymer,” eXPRESS Polymer Lett., 7(11):910-24).

Vinyl Sulfone Precursors

Vinyl sulfone precursors are an inexpensive chemical commodity commonlyused in the textile industry. Vinyl sulfone precursors are used hereinbecause they have two reactive sites, one for linking to the epoxidegroups of the vegetable oil and the other for linking to one or morenatural materials. While there are a number of suitable vinyl sulfoneprecursors that are suitable for use in the bio-based adhesive describedherein, the para-ester is shown, for example, in FIGS. 8 and 10. Asshown in FIGS. 8 and 10, the NH₂ group on the vinyl sulfone precursorsserves as the reactive group that is used to open the epoxide ring andform a covalent chemical bond to the vegetable oil. As described in moredetail below, the vinyl sulfone precursors also have a reactive siteavailable for reacting with one or more natural materials.

It would be appreciated that suitable bi-functional linkers for use inthe methods described herein can possess other functional groups (e.g.,NH₂NH (a hydrazine) or OH (a phenol)) in place of the NH₂ group. See,for example, FIG. 10, where R₁ can be NH₂, OH, or hydrazine.

Methods of Using a Bio-Based Adhesive to Make Bio-Composite Materials

The bio-based adhesive described herein (e.g., the vegetable oil-basedcross-linking agent shown in FIG. 8) can be combined with one or morenatural materials. The mixture can be heated (e.g., a reactiontemperature of about 35° C. to about 85° C.) under basic conditions(e.g., a pH of about 8 to about 10) to produce a bio-composite material.

As used herein, one or more natural materials typically refer torenewable natural materials. Natural materials suitable for use in themethods described herein can include, without limitation, wood chips(e.g., pinewood shavings), wood particles, or hemp. In addition, naturalmaterials suitable for use in the methods described herein also caninclude, without limitation, waste material from one or more crops(e.g., cotton, corn, hay, wheat) or proteinaceous fibers such asfeathers.

It would be appreciated that one or more natural materials suitable foruse in the methods described herein include those materials havingaccessible surface hydroxyl groups and/or nucleophilic groups. While notwishing to be bound by any particular mechanism, a plurality of vinylsulfone groups in a bio-based adhesive as described herein (see, forexample, the vegetable oil-based cross-linking agent in FIG. 8) canreact with a plurality of neighboring hydroxyl groups on the naturalmaterial (e.g., cellulose fibers), which forms covalent bonds andresults in a rigid cross-linked structure. Under basic conditions, thevinyl sulfone precursors described herein also can react with othernucleophiles such as phenols in lignin or amino groups on protein-basedsubstrates. The chemistry of vinyl sulfone precursors is well-documented(see, e.g., Christie, Colour Chemistry, In RSC Paperbacks Cambridge:Royal Society of Chemistry, 2001, e-book).

In some embodiments, high pressure can be applied to the fiber-adhesivemixture during the heating process to produce hard and higher densityfiber-composite. As used herein, “high pressure” refers to a pressure ofabout 10 to about 2000 pounds per square inch (psi). The resultingbio-composite is non-toxic and exhibits desirable physical propertiessuch as high strength, light weight, and biodegradability.

The methods described herein can be readily incorporated into existingproduction facilities with only minor modifications, and the cost of themethods and materials described herein are expected to be at or belowthe cost of other current formaldehyde-free adhesives or resins such as,for example, PUREBOND® or ECOSPHERE BIOPOLYMER®. The reduced costs canbe attributable, at least in part, to reduced energy requirements forthe present methods compared to other commercial-scale cross-linkingmethods. For example, the temperature for the methods disclosed herein(e.g., about 35° C. to about 85° C.) is much lower than that used inother competitive technologies (e.g., 100° C. to about 140° C., see, forexample, Liu et al., 2006, J. Agric. Food Chem., 54(6):2134-7). Whenproduced in bulk using epoxidized soybean oil, the cost for making thebio-based adhesive described herein is estimated to be about $0.80 orless per pound.

The methods described herein for making the bio-based adhesive as wellas the methods described herein for using the bio-based adhesives withone or more natural materials to make bio-composite materials can beperformed in water and do not require the presence of an organicsolvent. Thus, the bio-composite materials produced by such methodscontain no volatile organic vapors.

In accordance with the present invention, there may be employedconventional techniques within the skill of the art. Such techniques areexplained fully in the literature. The invention will be furtherdescribed in the following examples, which do not limit the scope of themethods and compositions of matter described in the claims.

EXAMPLES

Part A: Reactive Lignin

Example 1—Preparation of an Azo-p-Ester Lignin Polymer

4-(Ethylsulfurate sulfonyl) aniline (para-ester) (11.2 g, 0.04 mole) wasadded to a 250 mL Erlenmyer flask containing 50 mL of water and 15 g ofice while being stirred vigorously. Sulfuric acid (H₂SO₄, 9 M, 2.2 mL,0.02 mole) was added and the mixture was then stirred for around 10 min.Sodium nitrite (NaNO₂, 2.76 g, 0.04 mole) was added as a solution in 20mL water subsurface to the p-ester solution. The resulting solutionmixture was stirred one additional hour at 0° C. Lignin (alkaline, 7.73g) was then added to the solution mixture. The pH of the mixture wasadjusted to 4-5 with solid sodium bicarbonate (NaHCO₃). The resultingsolution mixture was stirred for another hour before being poured into aglass pan and dried overnight at 65° C. 21.6 g of a dark red solidproduct was recovered.

Part B: Bio-Based Adhesives

Example 2—Preparation of the Vegetable Oil-Based Cross-Linker Adhesive

10 g (36 mmol) of para-ester (2-((4-aminophenyl)sulfonyl)ethyl hydrogensulfate, CAS 249489-5) was added to a 250 mL Erlenmeyer flask containing30 mL of water and 20 g of ice. The slurry was stirred until homogeneousand 1.8 g of 50% sulfuric acid (H₂SO₄) was added. 2.6 g of sodiumnitrite (NaNO₂) in 15 mL of water was added drop wise and sub-surface tothe mixture. The slurry was stirred at 0° C. for one hour. 18 g ofsodium sulfite (Na₂SO₃) in about 60 mL of water was added at 0° C. tothe slurry. The pH of the mixture was adjusted to between 5 and 6 with50% H₂SO₄ and the resulting solution was stirred overnight. The solutionwas added to a 400 mL beaker containing 9.0 g of epoxidized soybean oil(7.0% oxirane) and the mixture was stirred rapidly at 60-70° C. for 10hr. The resulting mixture can be used as is or dried to a solid.

Example 3—Preparation of a Bio-Composite from Wood Shavings

15 g of dried vegetable oil-based cross-linker adhesive compound wasadded to 8 g of corn starch and 30 mL of water. The mixture was stirredfor about 30 min until homogeneous. 25 g of ice was added to themixture, followed by 15 mL of saturated aqueous sodium carbonate(Na₂CO₃). This mixture was added to 40 g of pine shavings, mixed welland put into a press consisting of two round metal plates and a C-clamp.The press was placed in an oven at 70° C. for two hours. The disk wascooled, and then dried at 40-50° C. overnight, yielding a solid pressedwooden disk of about 51 g. See FIG. 11.

It is to be understood that, while the methods and compositions ofmatter have been described herein in conjunction with a number ofdifferent aspects, the foregoing description of the various aspects isintended to illustrate and not limit the scope of the methods andcompositions of matter. Other aspects, advantages, and modifications arewithin the scope of the following claims.

Disclosed are methods and compositions that can be used for, can be usedin conjunction with, can be used in preparation for, or are products ofthe disclosed methods and compositions. These and other materials aredisclosed herein, and it is understood that combinations, subsets,interactions, groups, etc. of these methods and compositions aredisclosed. That is, while specific reference to each various individualand collective combinations and permutations of these compositions andmethods may not be explicitly disclosed, each is specificallycontemplated and described herein. For example, if a particularcomposition of matter or a particular method is disclosed and discussedand a number of compositions or methods are discussed, each and everycombination and permutation of the compositions and the methods arespecifically contemplated unless specifically indicated to the contrary.Likewise, any subset or combination of these is also specificallycontemplated and disclosed.

What is claimed is:
 1. A process for preparing a lignin derivative, theprocess comprising: contacting a lignin with a diazonium compound ofFormula I:

wherein the contacting is performed in an aqueous solution having a pHof less than about 7; and wherein: Ar¹ is a 6-10 membered arylsubstituted by 1, 2, 3, or 4 independently selected R^(a) groups; L¹ isselected from the group consisting of —C₁₋₆ alkylene-, —Y—,—Y—C₁₋₆alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄ alkylene-; R¹is selected from the group consisting of —O—S(O)₂OH and —O—S(O)₂OR^(a)L² is selected from the group consisting of a bond, —C1-6 alkylene-,6-10 membered aryl, 5-10 membered heteroaryl, wherein the 6-10 memberedaryl, 5-10 membered heteroaryl is optionally substituted by 1, 2, 3, or4 independently selected R^(b) groups; each Y is independently selectedfrom the group consisting of O, S, S(O), S(O)₂, C(O), C(O)NR^(c),NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c); each R^(a) isindependently selected from the group consisting of C₁₋₆ alkyl, 6-10membered aryl, 5-10 membered heteroaryl, wherein the 6-10 membered aryl,5-10 membered heteroaryl is optionally substituted by 1, 2, 3, or 4independently selected R^(b) groups; each R^(b) is independentlyselected from the group consisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl,C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy; each R^(c)is independently selected from the group consisting of H and C₁₋₃ alkyl.2. The process of claim 1, wherein the diazonium compound of Formula Iis a compound of formula Ia:

wherein: L¹ is selected from the group consisting of —C₁₋₆ alkylene-,—Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄alkylene-; R¹ is selected from the group consisting of —O—S(O)₂OH and—O—S(O)₂OR^(a) L² is selected from the group consisting of a bond, —C₁₋₆alkylene-, 6-10 membered aryl, 5-10 membered heteroaryl, wherein the6-10 membered aryl, 5-10 membered heteroaryl is optionally substitutedby 1, 2, 3, or 4 independently selected R^(b) groups; each Y isindependently selected from the group consisting of O, S, S(O), S(O)₂,C(O), C(O)NR^(c), NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c); eachR^(a) is independently selected from the group consisting of C₁₋₆ alkyl,6-10 membered aryl, 5-10 membered heteroaryl, wherein the 6-10 memberedaryl, 5-10 membered heteroaryl is optionally substituted by 1, 2, 3, or4 independently selected R^(b) groups; each R^(b) is independentlyselected from the group consisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl,C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy; and eachR^(c) is independently selected from the group consisting of H and C₁₋₃alkyl.
 3. The process of claim 1, wherein the diazonium compound ofFormula I is a compound of formula Ib:

wherein: L¹ is selected from the group consisting of —C₁₋₆ alkylene-,—Y—C₁₋₆ alkylene-,—Y—C₁₋₆ alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄alkylene-; each Y is independently selected from the group consisting ofO, S, S(O), S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O), S(O)₂NR^(c),NR^(c)S(O)₂, and NR^(c); each R^(c) is independently selected from thegroup consisting of H and C₁₋₃ alkyl.
 4. The process of claim 1, whereinthe diazonium compound of Formula I is a compound of formula Ic:


5. The process of claim 1, wherein the aqueous solution has a pH ofabout 4 to about
 5. 6. The process of claim 1, further comprisingforming the diazonium compound from the corresponding amine precursorprior to contacting the lignin with the diazonium compound.
 7. Theprocess of claim 6, wherein forming the diazonium compound from thecorresponding amine precursor comprises contacting the amine precursorwith nitrous acid.
 8. The process of claim 1, further comprisingcontacting the lignin derivative with a basic aqueous solution to forman alkene lignin derivative of Formula II:

wherein: Ar¹ is a 6-10 membered aryl substituted by 1, 2, 3, or 4independently selected R^(a) groups; L¹ is selected from the groupconsisting of —C₁₋₆ alkylene-, —Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄ alkylene-; L² is selected fromthe group consisting of a bond, —C₁₋₆ alkylene-, 6-10 membered aryl,5-10 membered heteroaryl, wherein the 6-10 membered aryl, 5-10 memberedheteroaryl is optionally substituted by 1, 2, 3, or 4 independentlyselected R^(b) groups; each Y is independently selected from the groupconsisting of O, S, S(O), S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O),S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c); each R^(a) is independentlyselected from the group consisting of C₁₋₆ alkyl, 6-10 membered aryl,5-10 membered heteroaryl, wherein the 6-10 membered aryl, 5-10 memberedheteroaryl is optionally substituted by 1, 2, 3, or 4 independentlyselected R^(b) groups each R^(b) is independently selected from thegroup consisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl, C₂₋₆ alkenyl,C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy; and each R^(c) isindependently selected from the group consisting of H and C₁₋₃ alkyl;and the wavy line indicates the point of attachment to a phenyl group ofthe lignin.
 9. The process of claim 8, wherein the alkene ligninderivative of Formula II is a compound of formula IIa:

wherein: L¹ is selected from the group consisting of —C₁₋₆ alkylene-,—Y—, —Y—C₁₋₆ alkylene-, —Y—C₁₋₆ alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄alkylene-; L² is selected from the group consisting of a bond, —C₁₋₆alkylene-, 6-10 membered aryl, 5-10 membered heteroaryl, wherein the6-10 membered aryl, 5-10 membered heteroaryl is optionally substitutedby 1, 2, 3, or 4 independently selected R^(b) groups; each Y isindependently selected from the group consisting of O, S, S(O), S(O)₂,C(O), C(O)NR^(c), NR^(c)(O), S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c); eachR^(b) is independently selected from the group consisting of OH, NO₂,CN, SH, halo, C₁₋₆ alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ haloalkyl,and C₁₋₆ alkoxy; and each R^(c) is independently selected from the groupconsisting of H and C₁₋₃ alkyl; and the wavy line indicates the point ofattachment to a phenyl group of the lignin.
 10. The process of claim 8,wherein the alkene lignin derivative of Formula II is a compound offormula IIb):

wherein: L¹ is selected from the group consisting of —C₁₋₆ alkylene -,—Y—, —Y—C₁₋₆ alkylene-,—Y—C₁₋₆ alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄alkylene-; each Y is independently selected from the group consisting ofO, S, S(O), S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O), S(O)₂NR^(c),NR^(c)S(O)₂, and NR^(c); each R^(c) is independently selected from thegroup consisting of H and C₁₋₃ alkyl; and the wavy line indicates thepoint of attachment to a phenyl group of the lignin.
 11. The process ofclaim 8, wherein the alkene lignin derivative of Formula II is acompound of formula IIc:

wherein the wavy line indicates the point of attachment to a phenylgroup of the lignin.
 12. The process of claim 8, wherein the basicaqueous solution has a pH of about 8 to about
 12. 13. The process ofclaim 8, wherein contacting the lignin derivative with the basic aqueoussolution to form the alkene lignin derivative is performed at atemperature of at least about 50° C.
 14. The process of claim 8, whereincontacting the lignin derivative with the basic aqueous solution to formthe alkene lignin derivative is performed at a temperature of about 60°C. to about 80° C.
 15. The process of claim 1, further comprisingcontacting the alkene lignin derivative with a nucleophilic compound toform a functionalized lignin.
 16. The process of claim 15, wherein thenucleophilic compound is selected from the group consisting of apolyalcohol, a sugar alcohol, a monosaccharide, a disaccharide, anoligosaccharide, a polysaccharide, a polyether, and mixtures thereof.17. The process of claim 16, wherein the nucleophilic compound comprisesat least one functional group selected from group consisting of —OH,—NH₂, —SH, —ONH₂, and —NHOH.
 18. The process of claim 17, wherein thefunctionalized lignin is a compound of formula III:

wherein Ar¹ is a 6-10 membered aryl substituted by 1, 2, 3, or 4independently selected R^(a) groups; L¹ is selected from the groupconsisting of —C₁₋₆ alkylene-, —Y—, —Y—C₁₋₆ alkyene-, —Y—C₁₋₆alkylene-Y—, and —C₁₋₄ alkylene-Y—C₁₋₄ alkylene-; L² is selected fromthe group consisting of a bond, —C₁₋₆ alkyene-, 6-10 membered aryl, 5-10membered heteroaryl, wherein the 6-10 membered aryl, 5-10 memberedheteroaryl is optionally substituted by 1, 2, 3, or 4 independentlyselected R^(b) groups; each Y is independently selected from the groupconsisting of O, S, S(O), S(O)₂, C(O), C(O)NR^(c), NR^(c)C(O),S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c); each R^(a) is independentlyselected from the group consisting of C₁₋₆ alkyl, 6-10 membered aryl,5-10 membered heteroaryl, wherein the 6-10 membered aryl, 5-10 memberedheteroaryl is optionally substituted by 1, 2, 3, or 4 independentlyselected R^(b) groups each R^(b) is independently selected from thegroup consisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl, C₂₋₆ alkenyl,C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy; and each R^(c) isindependently selected from the group consisting of H and C₁₋₃ alkyl;the wavy line indicates the point of attachment to a phenyl group of thelignin; Z is selected from the group consisting of —O—, —NH—, —S—,—ONH—, and —NHO—; and group A is the nucleophilic compound.
 19. Aprocess for preparing a functionalized lignin, the process comprising:(i) contacting a lignin with a diazonium compound of Formula Ito form alignin derivative,

wherein the contacting is performed in an aqueous solution having a pHof less than about 7; and wherein: Ar¹ is a 6-10 membered arylsubstituted by 1, 2, 3, or 4 independently selected R^(a) groups; L¹ isselected from the group consisting of —C₁₋₆ alkylene-, —Y—, —Y—C₁₋₆alkyene-, —Y—C₁₋₆ alkylene-, and —C₁₋₄ alkylene-Y—C₁₋₄ alkylene-; R¹ isselected from the group consisting of —O—S(O)₂OH and —O—S(O)₂OR^(a) L²is selected from the group consisting of a bond, —C1-6 alkyene-, 6-10membered aryl, 5-10 membered heteroaryl, wherein the 6-10 membered aryl,5-10 membered heteroaryl is optionally substituted by 1, 2, 3, or 4independently selected R^(b) groups; each Y is independently selectedfrom the group consisting of O, S, S(O), S(O)₂, C(O), C(O)NR^(c),NR^(c)C(O), S(O)₂NR^(c), NR^(c)S(O)₂, and NR^(c); each R^(a) isindependently selected from the group consisting of C₁₋₆ alkyl, 6-10membered aryl, 5-10 membered heteroaryl, wherein the 6-10 membered aryl,5-10 membered heteroaryl is optionally substituted by 1, 2, 3, or 4independently selected R^(b) groups; each R^(b) is independentlyselected from the group consisting of OH, NO₂, CN, SH, halo, C₁₋₆ alkyl,C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₁₋₄ haloalkyl, and C₁₋₆ alkoxy; each R^(c)is independently selected from the group consisting of H and C₁₋₃ alkyl;(ii) contacting the lignin derivative with a basic aqueous solution toform an alkene lignin derivative of Formula II:

wherein the wavy line indicates a point of attachment to a phenyl groupof the lignin; and (iii) contacting the alkene lignin derivative with anucleophilic compound to form a functionalized lignin.
 20. A process forpreparing a functionalized lignin, the process comprising: (i)contacting a lignin with a diazonium compound of Formula Ic to form alignin derivative,

wherein the contacting is performed in an aqueous solution having a pHof about 4 to about 5; (ii) contacting the lignin derivative with abasic aqueous solution at a temperature of about 60° C. to about 80° C.to form an alkene lignin derivative of Formula IIc

wherein: the wavy line indicates the point of attachment to a phenylgroup of the lignin; the basic aqueous solution has a pH of about 8 toabout 2; and (iii) contacting the alkene lignin derivative with anucleophilic compound to form a functionalized lignin.